They used a FAX machine to transmit weather charts, maps and orders during World War 2.
Early FAX machines were in use in the 19th century and became commercially used in the early 20th century (1920s era)
http://www.hffax.de/html/hauptteil_faxhistory.htm
1902 Prof. Dr. Arthur Korn, a German, demonstrated the first photo-electric scanning fax system. The previous methods had depended upon Bain’s contact-scanning technique. In 1902, Prof. Dr. Arthur Korn developed a photoelectric scanning system for the transmission and reproduction of photography, and in 1907, he established a commercial picture transmission system. This system eventually linked Berlin, London and Paris and became the world’s first facsimile network.
I remember during my time in the NAVY seeing a machine in a back room that was a transmitter/reciever of photos,documents etc. in use during WW2.
The object to be transmitted was "taped" to a drum that was scanned and sent. To receive a blank paper was "taped" to a drum and printed.
They were not as fast as today's FAX machines, but they were around.